1. Field of the Invention
The present invention relates to a stereoscopic microscope having a mechanism to allow identification of a shape of a cornea of an eye under inspection, suitable for use in an ophthalmologic operation,
2. Descripition of the Prior Art
A stereoscopic microscope has been widely used in the medical field such as for an operation or as a diagnostic tool, the research field and the industrial field, and is useful for enhancement of precision and safety of an operation. For example, when an eye, which is a precise optical system is diseased, appropriate measures recover its function is taken. When an operation is made for an eyeball, it is an important mission to recover the shape and the function thereof. In an operation for a cataract, it is an important factor for determining the success of the operation to recover the shape of the cornea by the operation. Accordingly, it is very effective to add a function of measuring the shape of the cornea to an operation microscope to allow measurement and display of the shapes of the cornea before and after the operation.
The prior art ophthalmologic operation microscope has only a function to project the eye under inspection has cannot allow the observation of the shape of the recovered cornea during the operation.
The optical system of the stereoscopic microscope is classied into three types, a fixed magnification type, a drum variable magnification type and a zoom variable magnification type.
The zoom variable magnification type preferably is used for the operation, because different magnifications are required in different stages of the operation.
However, when the magnification is changed during the operation, the measurement of the shape of the cornea varies with the magnification. As the measurement varies in spite of the fact that the same object is observed, there is confusion in analyzing the measurements. As a result, in the prior art microscope, a characteristic of the zoom variable magnification is not fully utilized.